After a week of controversy caused mainly by FIFA president Sepp Blatter's comments about racism, UEFA will hope that action on the pitch dominates this week's Champions League headlines as the group stage reaches crunch time.

Former European champions Manchester United, Bayern Munich, Inter Milan and Ajax Amsterdam will bid to seal their places in the last 16 and join Real Madrid, AC Milan and holders Barcelona in the knockout rounds.

English trio Arsenal, Manchester City and Chelsea can also take their places with a match to spare while this season's surprise packages APOEL Nicosia will become the first team from Cyprus to reach the last 16 if they win at Zenit St Petersburg.

Qualifying places are still open in seven of the eight groups. Only Group H is settled, with Barcelona and AC Milan qualified and BATE Borisov of Belarus and Viktoria Plzen vying for the consolation of a Europa League spot.

Napoli and Manchester City meet in Group A at the Sao Paolo on Tuesday looking to advance, with, almost certainly, group leaders Bayern Munich, who would reach the last 16 with a home win over Villarreal.

Napoli, erratic in Serie A, are unbeaten in 10 home matches since they returned to European competition in 2008 following a 13-year absence.

"It won't be at all easy, as City are a team of phenomena," Walter Mazzari said. "Roberto Mancini is right when he says they have no reason to envy Barcelona or Real Madrid. We'll try to the bitter end to go as far as possible."

City made their Champions League debut with a 1-1 draw against Napoli and have gone from strength to strength since, making it 11 wins out of 12 in the Premier League on Saturday with a 3-1 win over Newcastle United.

Mancini knows Napoli well from his days in Serie A.

"It will be an incredible atmosphere there under the lights where Napoli almost always win," he said.

Italian teams have done surprisingly well so far with only two defeats in 12 outings and while mainly pride will mainly be at stake when Milan and reigning champions Barcelona meet at the San Siro in Group H, 2010 European champions Inter Milan will hope to qualify by avoiding defeat at Trabzonspor in Turkey.

Inter need just a draw to advance from Group B and have won all three games in Europe since Claudio Ranieri replaced Gian Carlo Gasperini.

However, they could be without playmaker Wesley Sneijder who was injured in the warm-up for the game against Cagliari on Saturday.

The English teams have also done well with Arsenal, Chelsea and Manchester United all unbeaten and top of their groups and City losing just once.

Chelsea, beaten 2-1 at home by Liverpool on Sunday and in a domestic slump with three defeats in four matches, top Group E and will go through with victory at Bayer Leverkusen and their former midfielder Michael Ballack.

Arsenal also face German opposition when Borussia Dortmund travel to London and the hosts will seal their place in the last 16 with victory.

Dortmund gave themselves a huge confidence boost with a 1-0 win at Bundesliga leaders Bayern Munich on Saturday but only a victory at Arsenal will keep them in contention and the Londoners have lost only one of their last 36 home matches in the competition.

Matches between Manchester United and Benfica have a special resonance following their epic clashes in the 1960s including the 1968 European Cup final which United won 4-1, but United are favourites to win the Group C match at Old Trafford especially of the visitors are without striker Javier Saviola who has a knee problem.

An injury-depleted Ajax Amsterdam, second to Real Madrid in Group D, travel to Lyon with serious attacking problems as third-choice central striker Dmitry Bulykin sustained a knee injury in Saturday's 2-2 draw against NAC Breda.

With Kolbeinn Sigthorsson and Luuk de Jong already out for lengthy spells, coach Frank de Boer might have to adjust his tactical plans as winger Derk Boerrigter will also stay at home with back problems.

Ajax need a score draw to secure a place in the knockout phase.